It is a silver goeland, Its somewhat severe look is underlined with a red line. It is an area of bare skin called an orbital circle. It is more or less visible depending on the mood of the bird. It’s a way to communicate with fellow humans.
The more angry the goeland is, the more red his "eyes" are!
For food, the chicks tap on the red spot on their parents' beaks. This automatically causes the regurgitation of a fish puree they are fond of!